Sieve liner



May 14, 1935. H. B. RICE 2,001,631

SIEVE LINER Filed Sept. 19, 1933 Patented May 14, 1935 SIEVE LINER HarryB. Rice, Houston, Tex., assignor to Vacuum Belting Cloth CleanerCorporation, Houston, Tex., a corporation of Delaware i ApplicationSeptember 19, 1933, Serial No. 690,140

' 4 Claims.

My invention relates to liners for sieves or.

sifting screens and particularly to liners for devices of this characterwhich are commonly used for sifting or screening fine materials such '5as flour, talcum powder and tooth paste.

Bolting or sifting screens employed for such purposes, and particularlythose which operate- With a vibratory or gyratory motion, are generallyprovided with screen cloths .of silk or other thin fabric,- stretchedupon and secured to an open frame or grate. This supporting frame isusually constructed of wooden strips, bars orsections nailed orotherwise secured together, the area within the frame being divided intocompartments by cross bars, strips or partitions. Upon the innersurfaces of the frame so formed and partitioned marginal liners arecustomarily secured by nails or other suitable fastening means. Thesieve liners heretofore known and 1.9-. used have been made of fabricstrips or of wooden sections. Liners of either of these types, being ofa more or less porous nature, absorb a certain amount of-moistureandcause particles of the substances being screened to adhere to and remainupon them; Particles of the material being sifted become lodged in theangular corners of the liners upon the frame and in the crevices of thejoints between adjacent liner sections. These liners are alsoobjectionable because they wear out rapidly and have to be replacedfrequently.

Liners formed of'metal strips or plates secured together would belittle, if any, more satisfactory than the objectionable wooden orfabric liners.

same angular corners and crevices for catching particles of material, asare present in the Wooden line'rsr The increased weight and cost of themetal frames would also be undesirable. Moreover, unless they wereformed of some special expensive metal they would be liable to rust anddeposit particles of rust or scale in the screened materials.

These objections and defects areespecially important and-serious in thecase of screens ,or sieves used for screening food materials (forexample, flour or salt) or toilet or pharmaceutical powders orpreparations (for example, talcum powder, tooth powder, tooth paste andsoda). In the screening of materials of this general character it is notonly important, but vitally essential, that the cleanliness and purityof the screened material be preserved. Caking of particles of thematerial upon the frame or liner or in corners or crevices, and/or theintroduction of such old and stale caked particles or fragments of dirt,rust or other foreign matter, results in an impure and otherwiseunsatisfactory screened product.- 7

. The marginal inner liners heretofore provided Such metal liners wouldhave the are otherwise objectionable. They are usually secured inposition upon the screen frame. by numerous nails driven through theminto the wooden frame. A liner for a single sieve compartmentisordinarily formed of four strips or sections, each held in place byfrom six. to ten nails. In the operation of the screens it is necessaryfrom time to time to remove the liners for cleaning purposes or toreplace worn liners.

Each time; this is, done from twenty-four to forty nails must bewithdrawn from and re-' inserted into the wooden frame. This results ingreat damage to the frame, rendering it incapableof having linersattached to it and compelling it to be discarded and replaced whileitisotherwise in satisfactory operative condition.

One of the principal objects of my present invention is the provision ofa sieve or screen liner which will present a smooth unbroken sur face tothe material on the screen, and which will be free of joints, crevicesor recesses in,

which the material might lodge and be retained.

Anotherobject is the provision of a unitary sieve liner of convenientand efficient form which may readily be applied to and removed orcomposition which is readily adjustable to sieves of different sizes,shapes or dimensions, and which will, by reason of its resiliency,increase the activity and promote the effective functioning of sievecloth cleaners operatively positioned relative to the sieve A stillfurther object is the provisionfof an integral sieve liner, which may bereadily and economically produced of rubber, rubber composition or othersuitable preferably resilient moldable material. I

The invention by which these objects are realized comprises a linershaped, formed and constructed in the manner illustrated in the,accompanying drawing and more fully explained and defined in thefollowing description and claims: a

In the drawing: I Figure l is a perspective view of the preferred formof the liner which constitutes my inven-, tion.

Figure 2 is a top plan view of a sifting screen or sieve comprising amarginal frame and partitions with sieve cloth and cleaner support se-25; from a screen, with comparatively little, if any,

Figure 4 is a central sectional view of my cloth cleaner shown in Figure3.

My liner is designed to be applied to a frame B, preferably composed 'ofside pieces or strips II and end pieces l2, and supporting a sieve clothl3 of silk or'other suitable fabric anda sieve cleaner support I4preferably of reticulated liner. The inner sides, 3 of the liner may. be

beveled, curved or rounded, but are preferably flat plane surfaces withthe corners! rounded.

While my liner, is preferably of rectangular form or shape, and is soillustrated, it may be of circular or annular form or of any shapeand/or dimensions necessary to adapt it to 7 screen frames of othershapes and dimensions.

The necessity" of producing liners of different dimensions is largelyeliminated, however, by the flexibility and elasticity of my liner, any

individualliner being capable of considerable stretching to fit framesof different shapes and sizes.

The adaptability and adjustabilty of my liner are of particularimportance and usefulness. The liner is made in one piece, preferably ina mold of suitable construction. It combines the desirable attributes offirmness, resiliencypflexible adjustability and long life. Thesecharacteristics are inherent in the liner by reason of the material ofwhich it is formed. The material best suited forv this purpose is softsmooth rubber of non-blooming stock, cured without sulphur, or closelysimilar rubber composition.

Such" materials are well known, being commonly employed in the variousarts for cushioning and shock absorbing purposes.

My invention is not limited to the use of any specific rubber or rubbercomposition, as any kind of rubber, rubber composition or other suit-'able plastic composition may be employed which is adapted to form atough wear-resisting and semi-rigid but flexible and resilientrubber-like strip or frame of smooth texture.

My liner is'readily secured in pos'ition'and,

because of its'resiliency, clings or adheres closely to theframe. It maybe nailed or otherwise secured to the frame. If .nails are used one ortwo small nails in each of the rounded and preferably thickened cornerswill be sufficient. Byvirtue of its flexibility a liner embodying myinvention is not restricted in its use to any one frame of certain shapeor dimensions. The liner may be, and preferably is, made sufficientlythin to have considerable flexibility and elasticity and anyone or moreof its sidesmay consequently be stretched lengthwise in the same manneras an ordinary heavy rubber band. In this way my liner may be stretchedto fit sieve frames of various sizes and shapes. It may be used eitherabove or below the screen cloth, or inboth locations, where theparticular frame construction permits or renders such use of the linerpossible and desirable or useful. The liner is easily and quicklyapplied and firmly held in, place. It is usually applied and secured tothe frame in' stretched condition.

Under certain conditions the natural resiliency of the liner exertssufficient gripping action to hold it in position when it is compressedand sprung into the frame. Various other modes of securing theliner' inposition maybe used.

)If nails are employed, only 'a few small nails in the corners will beneeded, no nails or other fastening means between the corners beingrequired. In this respect my liner is a considerable. improvement overthe fabric and sectional wooden liners heretofore known and now in use,which require nails entirely around all sides, the total numbernecessary being several times the number required for my liner. Thedamage to the wooden sieve frames which results from the repeateddriving andwithdrawal of so large a number of nails is obviated orgreatly lessened by the use of my one'piece resilient liner. The

application of my liner to a screen frame is much more simple than thematter of securing 'fabric or sectional wooden liners in place.

There is a considerable saving of time and trouble.

My liner also possesses the advantage of completely filling. up thecorners of the frame, which the fabric liners now in use cannotaccomplish, and of eliminating altogether the existence ,of the angularcorners, joints and crevices always present in the wooden liners now inuse, which are formed of four sections. One of the points of superiorityof my liner, therefore, is that it is clean andsanitary, particularlybecause it is not porous. permits no particles of material'to cling toit, and affords no recesses for the col lection of particles of dirt orfor the hiberna tion of weevils. r I r An additional feature ofadvantage of my liner, as compar'edwith the known fabric and woodenliners. is its usefulness in association with sieve cloth cleaners.

In order to obtain a satisfactory sifting operation, it is essentialthat the meshes of the screen cloth be maintained in free and opencondition. To this end cleaners of various kinds have been designed toknock or jar the fine screen cloth of vibrating screens-so as to loosenthe material from the meshes of the screen and throw it upwardly. Theresult sought by all such devices is to maintain the mass of material ina constant, dancing motion. The efficiency of such devices dependsinlarge measure upon their activity, i. e., upon the rapidity and extentof their movement. Among the schemes proposed for accomplishing thedesired result, balls or other loose pieces of metal have'been arrangedupon a reticulated or screen-like support (similar to the cleanersupport, l4 shownj herein), the support being disposed below the screencloth l3 to be cleaned and so spaced from it that the loose pieces wouldat frequent intervals strike the screen cloth when the cloth and thelower support werevibrated together.

A form of screen cloth cleaner device which I have invented and found tobe more efficient and generally more satisfactory than prior'devicescomprises a soft body of rubber or rubber composition in the form of asubstantially flat upper surface and having upon its lower'surface anintegrally formed rounded'knob, This device is described and claimed inacopending application, Serial No. 652,215, filed January 17. 1933.

In use, one or more of my cleaner devices are placed upon a support llof wire, fabric orany other suitable material immediately beneath thescreen cloth 13 to be cleaned. The screen cloth l3 and support l4 may besecured in fixed relationship in the frame A, which may be vibrated,oscillated, gyrated or otherwise agitated by any suitable mechanism (notshown) in the performance of sifting or screening operations. Both thecleaner device and sieve liner, however, are adapted to be used uponsieves or screens of this general character whether the support I4 isfixed to vibrate with the screen cloth l3 or is separate therefrom anditself either movable or stationary. The screen cloth may be of anysuitable character and mesh. The support I4 is preferably reticulatedand of relatively coarse mesh, but may be imperforate where the machinein which it is used is of such design as to permit.

In the operation of the sieve or screen illustrated herein, the screencloth l3 and support M are vibrated or otherwise agitated as a unit. Thecloth cleaner devices C rest upon their rounded knobs 22 upon thesupport l4, their upper surfaces being either in contact with the screencloth or sufficiently close thereto to contact therewith during theoperation of the screen. Agitation of the frame carrying support l4 andscreen cloth I3 gives the cleaner devices a slight but eificientbounding or bouncing movement accompanied by constantly varying tiltingmovements occasioned by the unbalanced condition of the devices upontheir rounded knobs 22. The cleaner devices consequently strike thescreen cloth I3 at frequent intervals but at different points andvarying angles. Sometimes the entire top face of the device strikesflatly against the under side of the screen cloth, on which occasionsthe recess 24 exerts an action similar to that of a vacuum cup; thedevice attaches itself momentarily to the cloth and is released by thecontinued vibration of the screen cloth l3 and support I 4. At othertimes first one edge of the cleaner and then another is tilted againstthe screen cloth. This tilting, bounding and cupping action iscontinuous.

The cleaner is ordinarily sufficiently active and its contacts with thescreen cloth sufiiciently violent to afford ample and satisfactory clothcleaning action. Its eflicie'ncy is increased, however, when a screencloth cleaner C of this character is used in a screen fitted with theresilient liner A disclosed in my present application. When so used, thecleaner device of resilient material, in the course of its movement uponthe vibrating support I4, comes frequently into contact with the linerA, and rebounds therefrom, the rebounding action being amplified by theresiliency of the liner.

These contacts occur at points on the liner between the corners, thecleaner practically never striking the liner at the corners where thenails may be located.

Hence, no matter how badly worn my liner may become, the cleaner deviceused with it cannot be injured by contact with exposed nail heads. Inthis respect my resilient liner is superior to the old fabric and woodenliners which are secured by nails throughout their extent. When theseold liners begin to wear away through continued use, the nail heads areleft exposed along the sides of the frame, between corners where thecleaner repeatedly strikes. The result, of course, is excessive wear ofand damage to the cleaner device. The avoidance of this damage by theuse of my liner is a distinct benefit, regardless of the type or form ofcleaner device which may be associated with it As previously indicated,the cleaner device 0, which is most advantageous in connection with myliner A, comprises a body 2| preferably in the form of a generally fiatrectangular shape, provided on its under side with a rounded supportingknob or button 22 preferably integral with the body 2|. The knob orbutton may be made entirely of the same rubber, rubber composition orother resilient plastic material of which the body 2| is composed, thewhole being formed integrally preferably by moulding. Or the knob may becomposed wholly or partially of a rounded metal head, cap or insert 23seated upon or embedded in the knob 22, in order to provide a relativelyhard wear-resisting sur face at the point of most frequent contact withthe metal of the support 14. The preferred manner of producing thedevice is to mold the entire device in one piece with the metal insert23 incorporated as a part of the integrally formed rounded knob 22.

The body 2| of the cleaner is preferably formed with a recess 24 on itsupper side. This recess may vary in size and shape, but for best resultsshould be circular, or substantially circular, and of a diameter anddepth sufiicient to effect a cupping or vacuum action upon the screencloth l3 when the upper surface of the body 2| comes into contact withthe cloth.

My cleaner device may be made of different shapes and proportions. Boththe cleaner and the linerdescribed herein may be used with sifting orshaking screens of different kinds for various materials as well asflour and the other substances specifically mentioned. My invention isnot limited to the dimensions of theliner or of the cleaner, asillustrated, the drawing merely showing the preferred form. ofembodiment of each.

I claim:

1. A liner for sieves comprising an integral frame-like body of rubbercomposition adapted to be secured to the inner surface of a sieve frame,and having relatively thin flexible side and end walls and relativelythick corners rounded on their inner surfaces.

2. A sifting apparatus comprising a frame, a screen cloth secured uponsaid frame and an integral endless elastic rubber liner secured to theinner surface of said frame adjacent said screen cloth and extendingentirely around the margin thereof.

3. A liner for sieves comprising an integral endless body adapted to besecured to the inner surface of a sieve frame, said body havingrelatively thin elastic portions adapted to be positioned against thewalls of said frame and spaced relatively thick portions on said body tofit the corners of said frame.

4. A sifting apparatus comprising a frame, a screen cloth secured uponsaid frame, and an endless elastic liner extending entirely around theinner surface of said frame adjacent said screen cloth and securedthereto in stretched condition.

HARRY B. RICE.

